BIOL1003 Lecture Notes - Lecture 13: Uracil, Cytosol, Polymerization

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1 Jul 2018

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DNA

Deoxy-ribonucleoside triphosphate (dNTP)- a nucleotide

RNA

Ribonucleoside triphosphate (rNTP)- a ribonucleotide

Structure of RNA

Similar to DNA

oSugar phosphate backbone linked by phosphodiester bonds

oBase sequence carries information

Different from DNA

oSingle stranded

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oDifferent sugar (ribose)

oOne different base: uracil (U) instead of thymine (T)

RNA is single stranded but forms anti-parallel double helix

Why do we need RNA?

DNA is single-copy

oEach cell has the same number of DNA molecules

oCells have copies of genes they don’t need

The information needs to get to where it is needed (usually not the nucleus)

Different genes need to be represented in different copy numbers

Structure and function of DNA and RNA

DNA RNA

Lacks second hydroxyl group- more

compact

Always double stranded- all of the

hydrogen bonds of the bases are

always protected

Won’t bump into individual

oxygens- wind it really tightly into

chromosomes

DNA has its structure because its

main function is to store genetic

information and has to last a long

time

Has extra hydroxyl group- isn’t

always protected so doesn’t last as

long

Oxygens keep bumping into each

other- keeps rotating around the

axis trying to find an equilibrium

point and then flips back again-

much more motile as it needs to get

places and move around

Doesn’t last long- so they can switch

between signals very quickly

Signal selection and amplification

Up to 20,000 human genes overall

mRNA transcription: over 200,000 transcripts of around 10,000 genes expressed in a

cell

Single genes may be expressed at levels between 1-10,000 mRNA copies per cell

mRNA degrades quickly, has to be replenished to maintain pool

mRNA reflects what the cell is doing

RNA disappears very quickly so that if there is a change in the environment the

entire process can be taken over by something more up to date, localised and

adequate for those conditions

Transcription (RNA synthesis)

Complementary base pairing used to produce an RNA strand that carries the same

information as the DNA template

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Document Summary

Similar to dna: sugar phosphate backbone linked by phosphodiester bonds, base sequence carries information. Different from dna: single stranded, different sugar (ribose, one different base: uracil (u) instead of thymine (t) Rna is single stranded but forms anti-parallel double helix. Dna is single-copy: each cell has the same number of dna molecules, cells have copies of genes they don"t need. The information needs to get to where it is needed (usually not the nucleus) Different genes need to be represented in different copy numbers. Always double stranded- all of the hydrogen bonds of the bases are always protected. Won"t bump into individual oxygens- wind it really tightly into chromosomes. Dna has its structure because its main function is to store genetic information and has to last a long time. Has extra hydroxyl group- isn"t always protected so doesn"t last as long.

Related Questions

Multiple answers to each question might be possible!

You decide to identify the CFTR mutation by analyzing the genomic DNA of your patients compared to healthy individuals. You specifically are looking to see whether a specific 3' gene truncation has occurred in the patients. You will determine this using hybridization techniques with samples from healthy and CF patients. Which of the following will allow you to accomplish this?

	Using an RNA probe complementary to the region not removed by the truncation.
	Using an RNA probe complementary to the region removed by the truncation.
	Using an DNA probe complementary to the region not removed by the truncation.
	Using an DNA probe complementary to the region removed by the truncation.

To conduct the hybridization experiment, you are trying to decide between using a DNA or RNA probe. Which would be ideal to use and why?

	As both are composed of nucleic acids, using either would result in identical results.
	An RNA probe because RNA has uracil bases.
	An RNA probe because it could also be used in a translation experiment.
	A DNA probe because it is more stable than RNA.
	A DNA probe because RNA cannot bind to DNA.

One step of the Hershey/Chase experiment involved blending the virus/cell mixture before centrifugation and probing the pellet for radioactivity. Why was the blending step necessary?

	To collect the bacteria at the bottom of the tube.
	To break open the bacteria to release the genome.
	To separate the bacteria from the bacteriophages.
	To be able to detect the radioactivity.

Imagine Hershey/Chase had used an RNA virus (genome composed of RNA) instead of a DNA virus in their experiment. Would radioactivity still have been found in the pellet?

	No, because only DNA can be labeled with radioactivity.
	No, because the RNA genome would not enter the bacteria upon infection.
	No, because while DNA and RNA nucleotides are similar, they are not identical.
	Yes, because DNA and RNA nucleotides are similar.
	Yes, because genome in any form (DNA, RNA, protein) would be labeled similarly.

The human genome consists mostly of non-coding DNA. Which of the following are benefits of this?

	Random DNA mutations generally won't affect RNA and protein function.
	It is faster to duplicate the genome when these are present.
	The existence of introns can lead to multiple variations of proteins encoded by a single gene.
	It is unlikely transposons would exist in the genome if there was too much protein coding DNA.

Explain the 5â to 3â directionality of a DNA stand.

	It is due to the fact that the free 5â carbon is on one end and the free 3â carbon is on the other
	It is due to the fact that new nucleotide are added to the 5â carbon of the previous nucleotide
	It is due to the fact that there are 3 phosphate groups attached to the 5â carbon
	It is due to the fact the complementary strand is 3â to 5â
	More than one of the above explain the 5â to 3â directionality

You accidentally add a mutant dNTP (which has an H instead of an OH connected to the 3â carbon) to a reaction where DNA is being replicated. Which of the following is true of this mutant dNTP?

	It can be incorporated into DNA strand but cannot form a phosphodiester bond with an incoming wild type dNTP
	It can be incorporated into a DNA strand but cannot base pair with a complementary nucleotide
	It can be incorporated into a DNA strand and can form a phosphodiester bond with an incoming dNTP, but only if it is another mutant dNTP
	It cannot be incorporated into a DNA strand.

Why does DNA polymerase utilize an RNA primer?

	DNA polymerase is unable to initiate strand synthesis but RNA polymerase can
	DNA polymerase can only add a dNTP to an rNTP
	DNA synthesis proceeds in the 3â to 5â when initiating strand synthesis
	Chromosomal DNA contains interspersed RNA fragments
	The RNA primer increases stability of the newly synthesized strand

rosehippopotamus950

1. Unlike DNA, RNA contains

deoxyribose

a double strand

phosphates

uracil

Nucleic acid structure

2. In transcription, uracil will bond with:

thymine

cytosine

adenine

guanine

Transcription

3. The first team of scientist to document the structure of DNA was:

Franklin and Wilkins

Watson and Crick

Pauling and Chargoff

None of the above

DNA structure

4. Organelles that synthesize protein are:

lysosomes

ribosomes

endoplasmic reticulum

golgi bodies

5. Most of the time in a cell's life, it's DNA is in the form of:

Chromatin

Chromatids

Replicated chromosomes

Spindle fibers

6. Uracil is a nitrogen base that pairs with adenine. Using this information, one could conclude that uracil is a:

Purine

Pyrimidine

Neither a purine or pyrimidine

Not enough information

7. a nucleotide does not consist of a:

polymerase

5-carbon sugar

phosphate group

nitrogen base

8. The genetic code in DNA of an individual depends on the sequence (order) of:

nucleotides

purines only

phosphates

sugars

9. Before a cell divides, it must duplicate its DNA in a process known as:

translation

transformation

transcription

replication

10. The basic unit (building block) of a protein is a (an):

carbohydrate

amino acid

lipid

hydrogen bond

11. Unlike DNA, RNA contains:

deoxyribose

a double strand

phosphates

uracil

12. The structure of DNA was first documented in:

1945

1953

1956

1962

13. In DNA replication, the new molecules produced are:

of unequal length

both assembled in the same direction

built with purines as the backbone

assembled in opposite directions

DNA replication

14. The "backbone" of DNA is composed of:

ribose and phosphates

deoxyribose and phosphates

ribose and uracil

deoxyribose and thymine

DNA structure

15. RNA differs from DNA in which of the following ways?

RNA is single-stranded

RNA contains ribose

RNA does not contain thymine

All of the above

DNA structure

16. Which of the following is NOT required for the transcription process itself?

RNA polymerase

DNA

uracil-containing nucleotides

ribosomes

skyhamster121

Question 1: (Select all that apply) Nucleotides are composed of which of the following?

A) A sugar molecule

B) DNA

C) Nitrogen-containing base

D) Phosphate group

QUESTION 2 (Select all that apply) Which is true about telomerase?

A) adds a short sequence to the 3â end of a chromosome

B) is NOT needed to complete DNA replication

C) is required to maintain telomere structure

D) contains an RNA template for telomere structure

Question 3: DNA polymerase III CANNOT start synthesizing DNA without a free 3â end of a nucleotide, which, in DNA replication, is an RNA nucleotide primer synthesized by DNA ____________. (fill in the blank)

cerisemuskrat602

BIOL1003 Lecture Notes - Lecture 13: Uracil, Cytosol, Polymerization

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